JPH07151973A - Zoom lens - Google Patents

Abstract

(57) [Abstract] [Purpose] It has five lens groups as a whole, and the moving conditions and refractive power of each lens group associated with zooming were properly set to provide high optical performance over the entire zoom range. Obtaining a compact zoom lens with a wide angle of view. [Structure] The first lens unit has a negative refracting power, the second lens unit has a positive refracting power, and the third lens unit has a positive refracting power in order from the object side. The combined refracting power at the wide-angle end is positive. Has a front lens group having a refractive power of 4 and a rear lens group consisting of a fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power, and when zooming from the wide-angle end to the telephoto end, The first, second, and third groups move so that the combined refractive power of the front group becomes weaker at the telephoto end than at the wide-angle end, and the fourth and fifth groups move so that their interval becomes narrower. The focal length of the i-th group is fi, the focal length of the entire system at the wide-angle end is fW, and the lateral magnification of the i-th group at the wide-angle end is βiW.
Was set appropriately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact zoom lens having a high zoom ratio and a wide angle of view, which is suitable for a lens shutter camera, a video camera, etc. The present invention relates to a zoom lens which is excellent in portability and has a shortened distance from one lens surface to an image surface.

[0002]

2. Description of the Related Art Recently, in a lens shutter camera, a video camera, etc., a compact zoom lens having a short total lens length has been demanded as the camera becomes smaller. In particular, lens shutter cameras are becoming smaller and smaller due to the development of peripheral technologies such as zoom driving electric circuits. There is.

Conventionally, a so-called two-group zoom lens composed of two lens groups having positive and negative refracting power has been mainly used as a zoom lens for a lens shutter. Since the two-group zoom lens has a simple lens structure and a moving mechanism at the time of zooming, it has advantages such as downsizing of the camera and relatively low cost. However, since the zooming action must be performed by only one lens group, the zooming ratio is about 1.6 to 2 times, and forcibly increasing the zooming ratio leads to enlargement of the lens system. At the same time, it becomes difficult to maintain high optical performance.

On the basis of a two-group zoom lens, the first group is divided into two lens groups having a positive refractive power, and as a whole,
A three-group zoom lens aiming at high zooming as a three-group configuration of positive and negative refracting powers is disclosed in, for example, Japanese Patent Laid-Open Nos. 3-282409, 4-37810, and 4-7651.
It is proposed in Japanese Patent Publication No. 1 and the like.

However, if an attempt is made to achieve a wide-angle zoom lens system having a half angle of view of 35 ° or more with this lens group configuration, the change in the entrance pupil position during zooming becomes large. For this reason, it becomes very difficult to suppress aberration variation due to zooming when achieving high zooming.

In addition to this, a zoom lens having a wide angle of view and a high zoom ratio, which has a half field angle at the wide-angle end of about 38 ° and a zoom ratio of about 3.5 times, has been proposed, for example. Kaihei 2-
72316 and JP-A-3-249614. However, these zoom lens systems have a large front lens diameter and a large overall lens length, and are not always sufficient as photographing lenses for compact cameras.

Particularly when applied to a camera using an external viewfinder, there is a problem that the lens barrel covers the photographing field of view of the viewfinder at the wide-angle end. Further, as a result, there arises a problem that the viewfinder arrangement and the camera form are restricted.

[0008]

Generally, in a zoom lens, if the refractive power of each lens group is strengthened, the amount of movement of each lens group for obtaining a predetermined zoom ratio is reduced, and the total lens length is shortened. High zoom ratio is possible. However, if the refracting power of each lens unit is simply increased, the aberration variation due to zooming becomes large, and particularly when achieving high zooming and widening the angle of view, it is necessary to obtain good optical performance over the entire zooming range. There is a problem that it becomes difficult.

The present invention is composed of five lens groups as a whole, the moving conditions and the refractive power of each lens group during zooming are appropriately set, and the photographing angle of view at the wide angle end is about 64 to 74 °.
It is an object of the present invention to provide a zoom lens having high optical performance over the entire zoom range with a zoom ratio of about 3.5.

[0010]

The zoom lens of the present invention comprises three lenses, in order from the object side, a first group having a negative refractive power, a second group having a positive refractive power, and a third group having a positive refractive power. And a rear lens group consisting of two lens groups, a front lens group having positive power and a fourth lens group having positive power and a fifth lens group having negative power. During zooming from the wide-angle end to the telephoto end, the first, second, and third groups move such that the combined refractive power of the front group weakens at the telephoto end as compared with the wide-angle end, The groups are characterized by movement such that their spacing is reduced.

[0011]

FIG. 1 is an explanatory diagram of the paraxial refractive power arrangement of the zoom lenses according to Examples 1 to 4 of the present invention. FIG. 2 is an explanatory diagram of the paraxial refractive power arrangement of the zoom lenses of Examples 5 to 7 in the present invention. 1 and 2, (A) is the wide-angle end,
(B) shows the telephoto end. 3 to 9 are lens cross-sectional views at the wide-angle end according to Numerical Embodiments 1 to 7 of the present invention, respectively. 10 to 30 are various aberration diagrams of Numerical Examples 1 to 7 of the present invention.

In the figure, LF is a front lens group having a positive refractive power, LR is a rear lens group, SP is a diaphragm, and IP is an image plane. Li (i = 1 to 1
5) is the i-th group. The arrows indicate the direction of movement of each lens group when zooming from the wide-angle side to the telephoto side.

The front lens group LF is composed of three lens groups, a first lens group L1, a second lens group L2 and a third lens group L3, and the combined refractive power at the wide angle end is positive. The rear lens group LR includes two lens units, that is, a fourth lens unit L4 having a positive refractive power and a fifth lens unit L5 having a negative refractive power.

At the time of zooming from the wide-angle end to the telephoto end, the first, second, and third groups both move toward the object side while the second group changes its relative positional relationship with other lens groups, and The composite refractive power of the front lens group moves so that it becomes weaker at the telephoto end than at the wide-angle end. Further, the fourth group and the fifth group move toward the object side so that the distance between them becomes narrow. At this time, Examples 1 to 1
In No. 4, the distance between the third group and the fourth group is made larger at the telephoto end than at the wide-angle end. As a result, the composite system of the third group and the fourth group, when viewed as an independent system, is designed to be multiplied as the magnification changes.

On the other hand, in Examples 5 to 7, since the refractive power of the fourth lens group is comparatively weak, the fourth group during zooming has an arbitrary movement locus so as to perform good aberration correction in the entire zooming range. It is good to do it like this. In the fifth to seventh embodiments, the distance between the third lens unit and the fourth lens unit is reduced at the telephoto end as compared with the wide-angle end in order to make it advantageous to shorten the overall lens length at the telephoto end.

In the present invention, the first group having negative refracting power at the wide-angle end and the second group having positive refracting power and the third group having positive refracting power are arranged at wide intervals, and the entire front group is retro. The focus type is used. As a result, the front side principal point of the front group is located on the image plane side, and it is possible to facilitate the widening of the field angle while preventing interference between the lens surfaces of the front group and the rear group. In addition, by making both the second and third lens units have positive refractive power, the second and third lens units share the strong positive refractive power as a retrofocus type in the front lens unit at the wide-angle end, thereby providing a wide image. It makes keratinization easy. Then, the fourth group is extended toward the object side to focus from an infinitely distant object to a short-distance object.

In the zoom lens of the present invention, the focal length f of the entire lens system is expressed by the following equation.

F = fA · β4 · β5 (β4> 0, β5> 0) (a) where fA is the composite focal length of the front group, and βi is the lateral magnification of the i-th group. .

In the present invention, as can be understood from the expression (a), when the magnification is changed from the wide-angle end to the telephoto end, the lateral magnifications β4 and β5 are increased and the combined focal length fA of the front lens unit is increased. By (weakening the composite refractive power of the front group), more efficient zooming is performed. In addition, the distance between the fourth lens unit having a positive refractive power and the fifth lens unit having a negative refractive power is made narrower (decreased) at the telephoto end than at the wide-angle end to give a zooming effect to the fifth lens unit. This makes it easy to achieve high zoom ratios. In addition, the rear group is configured to have a telephoto type (telephoto type) together with the front group having a positive refractive power so that the divergent (negative) refractive power is strengthened at the telephoto end, and the overall lens system is downsized. There is.

Particularly, in the present invention, by adopting the paraxial refractive power arrangement as shown in FIG. 1, the photographing angle of view is widened so that the focal length at the wide angle end becomes smaller than the diagonal length of the screen.

Specifically, the front group is the first group having negative refractive power,
It consists of the second lens group of positive refractive power and the third lens group of positive refractive power, and when zooming from the wide-angle end to the telephoto end,
Each lens group is moved so that the distance between the lens groups decreases and the distance between the second lens group and the third lens group increases.

In the first to fourth embodiments of the present invention, the first group and the third group are moved integrally for simplification of the mechanism, but they may be moved independently. According to this, the degree of freedom in design can be increased.

According to the present invention, in the above lens configuration, the focal length of the i-th group is fi, the focal length of the entire system at the wide-angle end is fW, and the lateral magnification of the i-th group at the wide-angle end is βiW.
0.4 <| f5 / fW | <1.5 (1) 1.1 <β5W <1.9 (2) I try to satisfy the conditions. As a result, high optical performance is obtained over the entire zoom range while further reducing the size of the entire lens system.

Next, the technical meanings of the above conditional expressions will be described.

Conditional expression (1) relates to the negative refracting power of the fifth lens group, and is mainly for effectively changing the magnification. If the negative refractive power of the fifth lens unit becomes weaker than the upper limit value of the conditional expression (1), the zooming effect of the lens unit becomes weak at the time of zooming, so that a constant zoom ratio is obtained. Therefore, the amount of movement of each lens group must be increased, which increases the total lens length.

Further, if the lower limit of conditional expression (1) is exceeded, at the wide-angle end, the lens system has positive composite refractive power of the first to fourth groups and negative refractive power of the fifth group. The action as a telephoto type becomes too strong.

As a result, the back focus of the lens system becomes too short, the outer diameter of the lens of the fifth lens unit becomes large in order to secure a constant amount of peripheral light, and at the same time, the refractive power of the lens unit becomes strong. Since it becomes too much, high-order field curvature and astigmatism occur, which makes it difficult to correct them.

Conditional expression (2) relates to the lateral magnification at the wide-angle end of the fifth lens unit.

Now, when the back focus of the lens system at the wide-angle end is BfW, it can be expressed as BfW = f5.multidot. (1-.beta.5W).

Therefore, in the present invention, the total length of the lens system and various aberrations are corrected in a well-balanced manner by appropriately setting the values of the conditional expression (2) together with the conditional expression (1).

If the imaging magnification becomes larger than the upper limit of conditional expression (2), the back focus becomes longer, but the first to fourth
The refracting power of the group becomes too strong, and the aberration variation becomes large. On the other hand, if the lower limit is exceeded and the imaging magnification becomes smaller, it becomes difficult to obtain a predetermined back focus.
This is not good because the lens outer diameter of the group increases.

In the present invention, it is preferable to configure each lens group as follows in order to widen the angle of view while reducing the variation of aberration due to zooming and to secure high optical performance over the entire screen.

(1) When the composite refractive power of the front group at the wide-angle end is φ _123W , 0.3 <fW · φ _123W <1.8 (3) 0.6 <f3 / It is preferable that the condition fw <2.5 (4) is satisfied.

Conditional expression (3) relates to the refractive power of the front lens group. When the upper limit of conditional expression (3) is exceeded, the refractive power of the front lens group becomes too strong at the wide-angle end, and the action of the telephoto system becomes strong. It becomes difficult to obtain the back focus. or,
When the value goes below the lower limit, the refractive power of the front lens group is weakened and the total lens length is increased. At the same time, the positive refractive power of the lens group of the rear lens group must be strengthened to maintain the focal length at the wide-angle end. It becomes difficult to balance various aberrations.

Conditional expression (4) relates to the positive refractive power of the third lens unit.
Since the refracting power of the group becomes weak, the amount of movement of the lens group at the time of zooming increases, leading to an increase in the lens system. On the other hand, when the value goes below the lower limit, high-order spherical aberration is strongly generated in the third lens group, which makes it difficult to correct it.

In the present invention, the upper and lower limits of the above conditional expressions (3) and (4) are set in order to correct the optical performance satisfactorily while shortening the total lens length at the wide-angle end in particular. 0.4 <fW · φ _123W <1.5 (3a) 0.9 <f3 / fW <2.0 (4a) Is good.

(2) When the combined refractive power of the front group at the telephoto end is φ _123T and the zoom ratio is Z, 0.8 <| f1 / fW | <5.0・ ・ ・ ・ ・ ・ ・ ・ (5) 0.7 <f2 / fW <6.0 ・ ・ ・ ・ ・ ・ (6) 0.15 <(Φ _123W / φ _123T ) / Z <0.8 ··· (7) 0.25 <β4W <1.2 ··· ··· (8) 0.1 <f5 · (1−β5W) / fW <0.7 ······························

Conditional expression (5) is based on the first system and the first system at the wide-angle end.
This is related to the ratio of the refractive powers of the groups. If the upper limit of conditional expression (5) is exceeded, the refractive power of the first group becomes too weak and the total lens length becomes large. On the other hand, when the value goes below the lower limit, the refracting power of the first lens unit becomes strong, so that it becomes difficult to secure a predetermined back focus at the wide-angle end.

Conditional expression (6) is based on the whole system and the second system at the wide-angle end.
This is related to the ratio of the refractive powers of the lens units. If the upper limit of conditional expression (6) is exceeded, the refractive power of the second lens unit will become weaker, so the amount of movement of the lens unit during zooming will increase and the lens system will increase. Imitate. On the other hand, when the value goes below the lower limit, the refractive power of the second lens unit becomes too strong, and accordingly, the refractive power of the third lens unit becomes too strong, which makes it difficult to correct spherical aberration, which is not preferable.

Conditional expression (7) relates to the zoom ratio of the front group. If the upper limit of conditional expression (7) is exceeded, the variable magnification share in the front group becomes too large, the refractive power of the lens groups in the front group becomes strong, and the amount of movement of each lens group during zooming increases. Come on. On the other hand, if the value goes below the lower limit, the variable power distribution in the rear group becomes too large, and the amount of movement of each lens group in the rear group increases in order to secure a predetermined variable power ratio, which is not preferable.

Conditional expression (8) relates to the lateral magnification of the fourth lens unit at the wide-angle end. If the upper limit of conditional expression (8) is exceeded, it will be difficult to obtain back focus at the wide-angle end, resulting in an increase in the lens outer diameter of the fifth lens group. On the other hand, when the value goes below the lower limit, the refractive power of the other lens units becomes strong in order to obtain a constant focal length, so that it becomes difficult to correct aberration variation during zooming. Furthermore, the focal length of the front group must be made longer, which is not good because the total lens length becomes longer.

Conditional expression (9) is mainly for appropriately setting the refracting power and lateral magnification of the fifth lens unit to obtain a predetermined back focus. If the upper limit of conditional expression (9) is exceeded, the back focus becomes longer than necessary at the wide-angle end, and the total lens length increases. On the other hand, if the value goes below the lower limit, it becomes difficult to obtain a predetermined back focus at the wide-angle end, and the outer shape of the fifth lens group increases, which is not good.

When the lateral power β4W of the fourth lens unit has a value range of 0.25 <β4W <0.6 when the refractive powers of the third and fourth lens units are relatively strong, It is desirable that conditional expressions (3) and (6) be in the following numerical ranges in order to achieve a compact and excellent optical system.

0.3 <fW · φ _123W / <0.9 (3b) 1.8 ≦ f2 / fW <6.0 (6b) On the other hand , When the third lens unit has a relatively strong refractive power and the fourth lens unit has a relatively weak refractive power, the lateral magnification β4 of the fourth lens unit is
When W takes a value range of 0.6 ≦ β4W <1.2, it is desirable that conditional expressions (3) and (6) be in the following numerical ranges in order to achieve a compact and excellent optical system.

0.9 ≦ fW · φ _123W <1.8 (3c) 0.7 <f2 / fW <1.8 (6c) (3) Negative The first group having a refractive power of 1 has at least one positive lens and at least one negative lens, and it is preferable that the lens surface of the negative lens on the image plane side has a concave surface facing the image plane side. .

(4) When an aspherical surface is introduced into the zoom lens of the present invention, the positive refracting power becomes weaker (the negative refracting power becomes stronger as it goes away from the optical axis to the lens surface closer to the object side than the diaphragm). If such an aspherical surface is introduced, it is possible to easily correct the curvature of field at the telephoto end, spherical aberration, and aberration variation due to zooming and aberration correction of the entire screen. If introduced into the fifth lens unit, mainly off-axis aberrations can be favorably corrected.

(5) The fifth lens unit having negative refractive power has at least 1
When the average values of the Abbe numbers of the materials of the positive lens and the negative lens in the fifth lens group are respectively ν5P and ν5N, each having a negative lens and a positive lens with a concave surface facing the object side, 12 <ν5N It is better to satisfy the condition −ν5P <35 (10). If the value exceeds the upper limit value or the lower limit value of the conditional expression (10), a large amount of fluctuation in chromatic aberration occurs during zooming, and it becomes difficult to correct this with other lens groups.

(6) The diaphragm is arranged in an air space existing between the lens surface of the second lens unit closest to the image plane and the lens surface of the fourth lens unit closest to the image plane. It is preferable because it can be disposed in the optical disk and the variation in aberration due to zooming can be suppressed. The diaphragm may be moved independently of the other lens groups during zooming, or may be moved integrally with the other lens groups. This makes it possible to dispose the diaphragm position in the vicinity of the position of the entrance pupil that moves during zooming, which is advantageous in preventing changes in field curvature aberration when the diaphragm is small.

Further, when performing focusing, when the focus group includes a diaphragm, moving the focus group with the diaphragm fixed on the optical axis reduces the drive torque for moving the diaphragm mechanism during focusing. It is possible because it is possible.

(7) If the focus group is divided into two or more lens groups and the distance between the lens groups is changed during focusing, it is possible to reduce aberration fluctuations during zooming and focusing. preferable.

(8) The focus in Examples 1 to 4 of the present invention is to move the fourth lens unit to the object side, and the focus in Embodiments 5 to 7 is to move the third and fourth lens units integrally to the object side. Focusing is performed from an object at infinity to a near object, but it may be performed by moving another lens group. For example, a method of moving the front group to the object side may be used.

If the back focus is sufficient at the wide-angle end, the fifth lens group may be moved to the image plane side. In this case, it is effective to reduce the lens outer diameter of the first lens group. Becomes It is also possible to simultaneously move two or more lens groups in the first to fifth groups.

Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side of the i-th lens. The refractive index of glass and the Abbe number.

Table 1 shows the relationship between the above-mentioned conditional expressions and various numerical values in the numerical examples.

The aspherical shape has an X axis in the optical axis direction, an H axis in the direction perpendicular to the optical axis, a positive light traveling direction, and R as a paraxial radius of curvature,
When A, B, C, D and E are aspherical coefficients,

[0056]

[Equation 1] It is expressed by

Numerical Example 1 F = 29.25 to 101.00 fNO = 1: 3.6 to 8.2 2ω = 73.0 ° to 24.2 ° R 1 = -136.48 D 1 = 1.30 N 1 = 1.80400 ν 1 = 46.6 R 2 = 44.39 D 2 = 0.41 R 3 = 53.68 D 3 = 3.00 N 2 = 1.80518 ν 2 = 25.4 R 4 = -226.68 D 4 = 1.10 N 3 = 1.66998 ν 3 = 39.3 R 5 = 35.15 D 5 = variable R 6 = 36.05 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 22.91 D 7 = 2.70 N 5 = 1.48749 ν 5 = 70.2 R 8 = -148.68 D 8 = Variable R 9 = 29.98 D 9 = 2.80 N 6 = 1.56873 ν 6 = 63.2 R10 = -61.97 D10 = Variable R11 = -20.25 D11 = 0.87 N 7 = 1.64769 ν 7 = 33.8 R12 = -96.09 D12 = 1.00 R13 = ∞ (Aperture) D13 = 1.00 R14 = -49.89 D14 = 0.78 N 8 = 1.48749 ν 8 = 70.2 R15 = 41.40 D15 = 2.10 N 9 = 1.84666 ν 9 = 23.8 R16 = -42.55 D16 = 5.60 R17 = 31.32 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 12.25 D18 = 5.50 N11 = 1.58313 ν 11 = 59.4 R19 = -25.47 D19 = Variable R20 = -31.70 D20 = 3.50 N12 = 1.84666 ν12 = 23.8 R21 = -17.94 D21 = 0.20 R22 = -22.10 D22 = 1.30 N13 = 1.80610 ν13 = 41.0 R23 = -317.84 D23 = 4.89 R24 = -18.10 D24 = 1.50 N14 = 1.78590 ν14 = 44.2 R25 = -63.65 aspheric coefficients R19 K = -1.81 × 10 ^{- 1} A = 0 B = 8.60 × 10 ^-6 C = 9.07 × 10 ^-8 D = -1.91 × 10 ^-9 E = 0

[0058]

[Table 1] (Numerical Example 2) F = 28.84 to 101.48 fNO = 1: 3.6 to 8.2 2ω = 73.8 ° to 24.1 ° R 1 = -107.63 D 1 = 1.30 N 1 = 1.80400 ν 1 = 46.6 R 2 = 29.11 D 2 = 3.50 N 2 = 1.80518 ν 2 = 25.4 R 3 = 188.37 D 3 = 0.38 R 4 = 248.08 D 4 = 1.10 N 3 = 1.60342 ν 3 = 38.0 R 5 = 33.55 D 5 = Variable R 6 = 33.40 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 19.67 D 7 = 2.70 N 5 = 1.48749 ν 5 = 70.2 R 8 = -176.19 D 8 = Variable R 9 = 29.75 D 9 = 2.80 N 6 = 1.56873 ν 6 = 63.2 R10 =- 53.64 D10 = Variable R11 = -19.54 D11 = 0.87 N 7 = 1.64769 ν 7 = 33.8 R12 = -93.56 D12 = 1.00 R13 = ∞ (Aperture) D13 = 1.00 R14 = -57.06 D14 = 0.78 N 8 = 1.48749 ν 8 = 70.2 R15 = 36.54 D15 = 2.10 N 9 = 1.84666 ν 9 = 23.8 R16 = -45.52 D16 = 4.85 R17 = 34.65 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 12.82 D18 = 5.50 N11 = 1.58313 ν11 = 59.4 R19 = -23.25 D19 = Variable R20 = -33.52 D20 = 3.00 N12 = 1.84666 ν12 = 23.8 R21 = -17.94 D21 = 0.15 R22 = -20.79 D22 = 1.30 N13 = 1.83481 ν13 = 42.7 R23 = -171.17 D23 = 4.39 R24 = -17.91 D24 = 1.50 N14 = 1.78590 ν14 = 44.2 R25 = -73.32 Aspherical surface coefficient R19 K = -3.37 × 10 ^-1 A = 0 B = 1.15 × 10 ^-5 C = -2.60 × 10 ^-8 D = -2.60 × 10 ^-10 E = 0

[0059]

[Table 2] (Numerical Example 3) F = 35.00 to 110.12 fNO = 1: 3.7 to 8.2 2ω = 63.4 ° to 22.2 ° R 1 = -209.03 D 1 = 1.30 N 1 = 1.80400 ν 1 = 46.6 R 2 = 127.91 D 2 = 0.41 R 3 = 143.81 D 3 = 3.00 N 2 = 1.80518 ν 2 = 25.4 R 4 = -90.07 D 4 = 1.10 N 3 = 1.66998 ν 3 = 39.3 R 5 = 50.47 D 5 = variable R 6 = 36.53 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 25.31 D 7 = 3.80 N 5 = 1.48749 ν 5 = 70.2 R 8 = -1105.62 D 8 = Variable R 9 = 36.04 D 9 = 3.20 N 6 = 1.56873 ν 6 = 63.2 R10 = -160.41 D10 = Variable R11 = ∞ (Aperture) D11 = 1.30 R12 = -21.36 D12 = 0.87 N 7 = 1.64769 ν 7 = 33.8 R13 = -289.38 D13 = 2.00 R14 = -78.97 D14 = 0.78 N 8 = 1.48749 ν 8 = 70.2 R15 = 46.97 D15 = 2.10 N 9 = 1.84666 ν 9 = 23.8 R16 = -48.67 D16 = 5.60 R17 = 32.95 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 14.36 D18 = 5.50 N11 = 1.58313 ν11 = 59.4 R19 = -27.03 D19 = Variable R20 = -30.81 D20 = 3.50 N12 = 1.84666 ν12 = 23.8 R21 = -19.27 D21 = 0.20 R22 = -30.53 D22 = 1.30 N13 = 1.80610 ν13 = 41.0 R23 = -115.65 D23 = 4.89 R24 = -18.03 D24 = 1.50 N14 = 1.78590 ν14 = 44.2 R25 = -118.71 aspheric coefficients ^{R19 K = 3.77 × 10 -1 A} = 0 B = 1.57 ^{10 -5 C = 3.17 × 10 -8} D = -8.36 × 10 -10 E = 0

[0060]

[Table 3] (Numerical Example 4) F = 35.00 to 110.00 fNO = 1: 3.7 to 8.2 2ω = 63.4 ° to 22.3 ° R 1 = −112.16 D 1 = 1.30 N 1 = 1.80400 ν 1 = 46.6 R 2 = 139.61 D 2 = 0.41 R 3 = 163.84 D 3 = 3.00 N 2 = 1.80518 ν 2 = 25.4 R 4 = -107.84 D 4 = 1.10 N 3 = 1.66998 ν 3 = 39.3 R 5 = 76.56 D 5 = variable R 6 = 36.05 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 25.55 D 7 = 3.80 N 5 = 1.48749 ν 5 = 70.2 R 8 = -389.95 D 8 = Variable R 9 = 45.54 D 9 = 3.20 N 6 = 1.56873 ν 6 = 63.2 R10 = -160.77 D10 = Variable R11 = ∞ (Aperture) D11 = 1.30 R12 = -20.88 D12 = 0.87 N 7 = 1.64769 ν 7 = 33.8 R13 = -233.98 D13 = 2.00 R14 = -159.29 D14 = 0.78 N 8 = 1.48749 ν 8 = 70.2 R15 = 46.64 D15 = 2.10 N 9 = 1.84666 ν 9 = 23.8 R16 = -49.54 D16 = 5.60 R17 = 35.02 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 14.70 D18 = 5.50 N11 = 1.58313 ν11 = 59.4 R19 = -28.48 D19 = Variable R20 = -19.90 D20 = 3.50 N12 = 1.84666 ν12 = 23.8 R21 = -17.24 D21 = 4.50 R22 = -16.95 D22 = 1.50 N13 = 1.77250 ν13 = 49.6 R23 = 483.96 Aspherical coefficient R19 K = 8.88 × 10 ^-1 A = 0 B = 1.21 × 10 ^-5 C = 1.06 × 10 ^-7 D = -1.47 × 10 ^-9 E = 0 Aspheric coefficient R22 K = 0 A = 0 B = 8.13 × 10 ^-6 C = 2.25 × 10 ^-8 D = -1.09 × 10 ^-11 E = 0

[0061]

[Table 4] Numerical Example 5 F = 28.80 to 10.91.6 fNO = 1: 4.30 to 9.00 2ω = 73.8 ° to 24.0 ° R 1 = -4116.96 D 1 = 2.60 N 1 = 1.51741 ν 1 = 52.4 R 2 = -51.61 D 2 = 0.88 R 3 = -32.32 D 3 = 1.20 N 2 = 1.77249 ν 2 = 49.6 R 4 = 28.95 D 4 = 2.80 N 3 = 1.84665 ν 3 = 23.8 R 5 = 265.48 D 5 = variable R 6 = 18.85 D 6 = 1.00 N 4 = 1.84665 ν 4 = 23.8 R 7 = 13.87 D 7 = 4.00 N 5 = 1.48749 ν 5 = 70.2 R 8 = -21.28 D 8 = 1.00 N 6 = 1.84665 ν 6 = 23.8 R 9 = -27.55 D 9 = Variable R10 = ∞ (Aperture) D10 = 3.00 R11 = -25.23 D11 = 1.36 N 7 = 1.80518 ν 7 = 25.4 R12 = -47.39 D12 = 0.14 R13 = -36.10 D13 = 6.85 N 8 = 1.67790 ν 8 = 55.3 R14 = -12.22 D14 = Variable R15 = -19.48 D15 = 2.50 N 9 = 1.58312 ν 9 = 59.4 R16 = -16.04 D16 = Variable R17 = -32.40 D17 = 3.00 N10 = 1.76181 ν10 = 26.6 R18 = -18.03 D18 = 0.17 R19 = -25.42 D19 = 1.30 N11 = 1.69679 ν11 = 55.5 R20 = -921.97 D20 = 4.59 R21 = -14.26 D21 = 1.50 N12 = 1.71299 ν12 = 53.8 R22 = 190.18 Aspherical surface coefficient R11 K = 4.91 A = 0 B = -1.20 × 10 ^-4 C = -6.48 × 10 ^-7 D = -1.53 × 10 ^-8 E = 0 Aspheric coefficient R15 K = 1.19 A = 0 B = 2.27 × 10 ^-5 C = 1.48 × 10 ^-7 D = 1.04 × 10 ^-9 E = 0

[0062]

[Table 5] (Numerical Example 6) F = 29.11 to 101.99 fNO = 1: 4.30 to 9.00 2ω = 73.2 ° to 23.9 ° R 1 = 95.83 D 1 = 3.20 N 1 = 1.51633 ν 1 = 64.2 R 2 = -53.56 D 2 = 0.61 R 3 = -35.06 D 3 = 1.20 N 2 = 1.80400 ν 2 = 46.6 R 4 = 17.05 D 4 = 3.28 N 3 = 1.84665 ν 3 = 23.8 R 5 = 74.99 D 5 = variable R 6 = 15.96 D 6 = 1.00 N 4 = 1.84665 ν 4 = 23.8 R 7 = 11.49 D 7 = 4.30 N 5 = 1.48749 ν 5 = 70.2 R 8 = -19.95 D 8 = 1.00 N 6 = 1.84665 ν 6 = 23.8 R 9 = -27.33 D 9 = variable R10 = ∞ (aperture) D10 = 3.50 R11 = -24.67 D11 = 2.30 N 7 = 1.80518 ν 7 = 25.4 R12 = -46.17 D12 = 0.19 R13 = -34.22 D13 = 1.20 N 8 = 1.65159 ν 8 = 58.5 R14 = 356.16 D14 = 5.50 N 9 = 1.74319 ν 9 = 49.3 R15 = -13.76 D15 = Variable R16 = -19.38 D16 = 2.50 N10 = 1.51633 ν10 = 64.2 R17 = -15.27 D17 = Variable R18 = -31.26 D18 = 2.30 N11 = 1.84665 ν11 = 23.8 R19 = -20.72 D19 = 0.71 R20 = -24.00 D20 = 1.30 N12 = 1.69679 ν12 = 55.5 R21 = 837.91 D21 = 3.73 R22 = -21.23 D22 = 1.50 N13 = 1.77249 ν13 = 49.6 R23 = 171.78 Aspheric coefficient R11 K = 4.71 A = 0 B = -8.41 × 10 ^-5 C = -1.40 × 10 ^-7 D = -8.96 × 10 ^-9 E = 0 Aspheric coefficient R15 K = -2.63 A = 0 B = -1.15 × 10 ^-4 C = 2.26 × 10 ^-7 D = -1.31 × 10 ^-9 E = 0

[0063]

[Table 6] (Numerical Example 7) F = 28.80 to 10.42 fNO = 1: 4.30 to 9.00 2 ω = 73.8 ° to 23.9 ° R 1 = -357.21 D 1 = 2.50 N 1 = 1.51741 ν 1 = 52.4 R 2 = -55.11 D 2 = 0.70 R 3 = -36.84 D 3 = 1.20 N 2 = 1.77249 ν 2 = 49.6 R 4 = 32.93 D 4 = 2.80 N 3 = 1.84666 ν 3 = 23.8 R 5 = 400.74 D 5 = variable R 6 = 19.18 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 12.66 D 7 = 3.70 N 5 = 1.48749 ν 5 = 70.2 R 8 = -31.67 D 8 = 0.80 R 9 = ∞ (Aperture) D 9 = Variable R10 = -23.72 D10 = 1.00 N 6 = 1.80518 ν 6 = 25.4 R11 = -48.78 D11 = 0.18 R12 = -33.17 D12 = 7.30 N 7 = 1.65844 ν 7 = 50.9 R13 = -11.89 D13 = variable R14 = -19.99 D14 = 2.50 N 8 = 1.58312 ν 8 = 59.4 R15 = -15.94 D15 = Variable R16 = -34.31 D16 = 2.90 N 9 = 1.76182 ν 9 = 26.5 R17 = -18.06 D17 = 0.39 R18 = -26.91 D18 = 1.30 N10 = 1.83480 ν10 = 42.7 R19 = -140.63 D19 = 4.84 R20 = -13.09 D20 = 1.50 N11 = 1.71299 ν11 = 53.8 R21 = 882.45 Aspheric coefficient R10 K = 4.60 A = 0 B = -1.07 × 10 ^-4 C = -8.17 × 10 ^-7 D = -1.35 × 10 ^-8 E = 0 Aspherical coefficient R14 K = 1.27 A = 0 B = 1.56 × 10 ^-5 C = 1.44 × 10 ^-7 D = 1.18 × 10 ^-9 E = 0

[0064]

[Table 7]

[0065]

As described above, according to the present invention, as a whole, it is composed of five lens groups, and by appropriately setting the moving conditions and the refractive power of each lens group during zooming, photographing at the wide-angle end is possible. It is possible to achieve a zoom lens having a high optical performance over the entire zoom range with an angle of view of about 64 to 74 degrees and a zoom ratio of about 3.5.

[Brief description of drawings]

FIG. 1 is an explanatory view of a paraxial refractive power arrangement of a zoom lens according to the present invention.

FIG. 2 is another explanatory diagram of the paraxial refractive power arrangement of the zoom lens of the present invention.

FIG. 3 is a lens cross-sectional view at a wide-angle end according to Numerical Example 1 of the present invention.

FIG. 4 is a lens cross-sectional view at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 5 is a lens cross-sectional view at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 6 is a lens cross-sectional view at a wide-angle end according to Numerical Example 4 of the present invention.

FIG. 7 is a lens cross-sectional view at a wide-angle end according to Numerical Example 5 of the present invention.

FIG. 8 is a lens cross-sectional view at a wide-angle end according to Numerical Example 6 of the present invention.

FIG. 9 is a lens cross-sectional view at a wide-angle end according to Numerical Embodiment 7 of the present invention.

FIG. 10 is an aberration diagram at the wide-angle end according to Numerical Example 1 of the present invention.

FIG. 11 is an intermediate aberration diagram of Numerical Example 1 of the present invention.

FIG. 12 is an aberration diagram at a telephoto end according to Numerical Example 1 of the present invention.

FIG. 13 is an aberration diagram at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 14 is an intermediate aberration diagram of Numerical example 2 of the present invention.

FIG. 15 is an aberration diagram at a telephoto end according to Numerical Example 2 of the present invention.

FIG. 16 is an aberration diagram at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 17 is an intermediate aberration diagram of Numerical Example 3 of the present invention.

FIG. 18 is an aberration diagram at a telephoto end according to Numerical Example 3 of the present invention.

FIG. 19 is an aberration diagram at a wide-angle end according to Numerical Example 4 of the present invention.

FIG. 20 is an intermediate aberration diagram of Numerical Example 4 of the present invention.

FIG. 21 is an aberration diagram at a telephoto end according to Numerical Example 4 of the present invention.

FIG. 22 is an aberration diagram at a wide-angle end according to Numerical Example 5 of the present invention.

FIG. 23 is an intermediate aberration diagram of Numerical Example 5 of the present invention.

FIG. 24 is an aberration diagram at a telephoto end according to Numerical Example 5 of the present invention.

FIG. 25 is an aberration diagram at a wide-angle end according to Numerical Example 6 of the present invention.

FIG. 26 is an intermediate aberration diagram of Numerical Example 6 of the present invention.

FIG. 27 is an aberration diagram at a telephoto end according to Numerical Example 6 of the present invention.

FIG. 28 is an aberration diagram at a wide-angle end according to Numerical Example 7 of the present invention.

29 is an intermediate aberration diagram of Numerical Example 7 of the present invention. FIG.

FIG. 30 is an aberration diagram at a telephoto end according to Numerical Example 7 of the present invention.

[Explanation of symbols]

 L1 1st group L2 2nd group L3 3rd group L4 4th group L5 5th group SP diaphragm IP image surface d d line g g line S. C Sine condition ΔS Sagittal image plane ΔM Meridional image plane

Claims (4)

[Claims] 1. A composite refracting power at a wide-angle end, which comprises three lens groups in order from the object side: a first group having a negative refracting power, a second group having a positive refracting power, and a third group having a positive refracting power. Has a front lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a rear lens group consisting of a fifth lens group having a negative refractive power, and at the time of zooming from the wide-angle end to the telephoto end. , The first, second, and third groups move so that the combined refractive power of the front group becomes weaker at the telephoto end than at the wide-angle end, and the fourth and fifth groups move so that their interval becomes narrower. A zoom lens that is characterized by 2. When the focal length of the i-th group is fi, the focal length of the entire system at the wide-angle end is fW, and the lateral magnification at the wide-angle end of the i-th group is βiW, 0.4 <| f5 / fW | < The zoom lens according to claim 1, wherein a condition of 1.5 1.1 <β5W <1.9 is satisfied. 3. When zooming from the wide-angle end to the telephoto end, each lens unit moves toward the object side so that the distance between the first and second groups decreases and the distance between the second and third groups increases. The zoom lens according to claim 1, wherein 4. When the composite refractive power of the front group at the wide-angle end is φ _123W , the condition of 0.3 <fW · φ _123W <1.8 0.6 <f3 / fW <2.5 must be satisfied. The zoom lens according to claim 2, wherein